Amelanotic acral lentiginous malignant melanoma

Misdiagnosis and Clinical Insights into Acral Amelanotic Melanoma-A Systematic Review

BACKGROUND

Acral amelanotic melanomas (AAMs), a rare subset of melanomas located on acral sites such as the palms, soles, and subungual areas, are diagnostically challenging due to their lack of typical pigmentation and often benign clinical appearance. Misdiagnosis is common, leading to delays in treatment and potentially worse outcomes. This systematic review aims to synthesise evidence on cases of AAM initially misdiagnosed as other conditions, to better understand their clinical and epidemiological characteristics, diagnostic pitfalls, and management strategies.

METHODS

A comprehensive search of the MEDLINE/PubMed, EMBASE, and SCOPUS databases was conducted up to March 2024. Case reports and small case series of AAMs initially misdiagnosed as other conditions were included. Data on patient demographics, clinical presentation, and diagnostic methods were collected and analyzed.

RESULTS

Of the 152 records identified, 26 cases from 23 articles met the inclusion criteria. A demographic analysis revealed that the gender distribution appears to be perfectly balanced, with an age range of 38 to 91 years. Misdiagnoses included non-healing ulcers or traumatic lesions (37.5%), benign proliferative lesions (29.2%) and infectious lesions (20.8%). The foot was the most affected site (53.8%). Notably, a histological evaluation was performed in 50% of cases involving the upper extremities, in contrast to only 7.1% of cases involving the foot and 0% of cases of the heel. This discrepancy suggests a reluctance to perform biopsies in the lower extremities, which may contribute to a higher misdiagnosis rate in these areas.

CONCLUSIONS

The underutilization of biopsy in the diagnosis of lower extremity lesions contributes significantly to the misdiagnosis and delay in treatment of AAMs. Especially when the clinical assessment and dermoscopy are inconclusive, biopsies of suspicious lesions are essential. Immunohistochemistry and markers such as PRAME are critical in differentiating melanoma from other malignancies such as clear cell sarcoma. This review highlights the need for increased vigilance and a proactive diagnostic approach to increase early detection rates and improve prognostic outcomes.

Acral melanoma with hyperkeratosis mimicking a pigmented wart

Acral lentiginous melanoma (ALM) of the sole sometimes has a hyperkeratotic appearance and mimics a pigmented wart. We report a case of an 81-year-old woman with an ALM on the left sole with hyperkeratosis. Due to its presentation it was difficult to make a correct diagnosis at the beginning. Finally we noticed several small, pigmented macules around the wart-like lesion with the parallel ridge pattern on dermoscopy, strongly suggesting acral melanoma. When a hyperkeratotic pigmented lesion on the sole is encountered, one should rule out melanoma by careful examination of the periphery of the lesion. Dermoscopy is a helpful adjunct for the diagnosis of an unusual case like this.

Development of a practical guide for the early recognition for malignant melanoma of the foot and nail unit

Background

Malignant melanoma is a rare but potentially lethal form of cancer which may arise on the foot. Evidence suggests that due to misdiagnosis and later recognition, foot melanoma has a poorer prognosis than cutaneous melanoma elsewhere.

Methods

A panel of experts representing podiatry and dermatologists with a special interest in skin oncology was assembled to review the literature and clinical evidence to develop a clinical guide for the early recognition of plantar and nail unit melanoma.

Results

A systematic review of the literature revealed little high quality data to inform the guide. However a significant number of case reports and series were available for analysis. From these, the salient features were collated and summarised into the guide. Based on these features a new acronym "CUBED" for foot melanoma was drafted and incorporated in the guide.

Conclusions

The use of this guide may help clinicians in their assessment of suspicious lesions on the foot (including the nail unit). Earlier detection of suspicious pedal lesions may facilitate earlier referral for expert assessment and definitive diagnosis. The guide is currently being field tested amongst practitioners.

[Melanoma in invisible naevus spilus]

BACKGROUND

Diagnosis of naevus lesions may be complex where they contain little or no pigmentation. Naevus spilus (or naevus on naevus) is, generally, readily identified by the difference in pigmentation between overlying and underlying naevi and healthy skin. Malignant transformation of naevus spilus is rare. We report two cases of melanoma in which surgical procedures revealed underlying melanocyte lesions, diagnosed at histology but undetectable on clinical examination.

PATIENTS AND METHODS

Two patients were operated for melanoma in which surgery, at a site remote from the melanoma, suggested incomplete relapse despite the fact that previous clinical examination had indicated healthy skin. A diagnosis was made of melanoma in invisible naevus spilus.

DISCUSSION

Diagnosis of melanoma in invisible naevus spilus may be suspected where several naevi are found together in a specific area. The main problem is the therapeutic stance to be adopted since complete excision of the underlying naevi is difficult in practice. Wood's light examination may be helpful.

Controversies in acral lentiginous melanoma

BACKGROUND

Acral lentiginous melanoma (ALM) is a subtype of melanoma initially described only two and half decades ago, but well-recognized by dermatologists today. However, several areas of controversy surround this entity.

OBJECTIVE

The primary aims of this article are to review the literature, highlight recent advances, and review some of the ongoing controversies in ALM.

METHODS

A review of the English language literature was performed.

RESULTS

Controversy continues to surround ALM, particularly in regard to diagnostic histologic and clinical criteria. This leads to difficulties when reviewing studies that evaluate the epidemiology, etiology, and prognosis of ALM.

CONCLUSION

Progress in understanding ALM requires the development of standardized diagnostic criteria.